The challenges of pertussis outbreaks in healthcare facilities: is there a light at the end of the tunnel?

Although classically recognized as a disease of infants and children, the reported incidence of Bordetella pertussis infection in adolescents and adults has increased at a remarkable rate over the past decade. During 2004, more than 25,000 cases of pertussis were reported to the Centers for Disease Control and Prevention (CDC), the highest total since 1959; of these, 34% were in individuals aged 11-18 years and 29% were in adults aged 19 years and older. 1 This increase in pertussis in adolescents and adults is likely due to several factors, including waning protection from childhood vaccination and natural infection, an increased appreciation of disease in this age group, and the improved ability of clini-cians to diagnose pertussis through the use of serologic methods. Whether this increase in pertussis incidence represents a true increase in disease or just reflects an improved recognition of disease remains unclear. However, what is clear is, first, that rates of pertussis are also increasing in infants, and second, that adolescents and adults serve as a source of contagion for infants and young children, who suffer the greatest morbidity, and even mortality, from pertussis. Despite high rates of routine pertussis vaccination among children , 2 rates of pertussis disease continue to climb, and it is becoming a major public health problem. Healthcare-associated outbreaks of pertussis also have been increasingly recognized and reported from a diverse range of healthcare facilities, such as residential homes for mentally or physically impaired persons, pediatric wards and nurseries , emergency departments, and hematology-oncology care units. 3-11 Such outbreaks are often the result of under-recognition of pertussis and subsequent failure to isolate patients with suspected infection, as well as the increasing incidence of pertussis among adults and adolescents. Healthcare workers (HCWs) are at increased risk for acquiring B. pertussis infection; one study estimates that there is a 1.7-fold increased risk for HCWs, compared with the general population. 12 A serologic analysis of samples from emergency department HCWs at Vanderbilt University Medical Center revealed annual incidence rates of 1.3 infections per 100 persons among emergency department resident physicians and 3.6 infections per 100 persons among emergency department nursing and patient care staff. 13 This increased risk is likely the result of regular contact with infected patients and waning protection from childhood vaccination or natural B. pertussis infection. Infected HCWs can then serve as vectors of infection to other susceptible contacts, including patients, other employees, and …